1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Determine the speed of the shuttle craft

  1. May 21, 2009 #1
    1. The problem statement, all variables and given/known data
    A spaceship moves away from the earth at a speed v, and fires a shuttle craft in the forward direction at a speed v relative to the ship. The pilot of the shuttle craft forward launches a probe at a speed v relative to the shuttle craft. Detrmine:

    a) the speed of the shuttle craft relative to Earth
    b) the speed of the probe relative to Earth

    3. The attempt at a solution
    Im just completely confused with this question, do i have to use Lorentz transformations?? but if so, how do i compute an answer?? plz can someone help, completely lost with this one.
  2. jcsd
  3. May 21, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    You can just use the velocity addition formula I suppose.
    Apparently someone else is working on the exact same question in this thread.
  4. May 21, 2009 #3
    ok for part a, i can use the LT to get u=2v/(1+v^2/c^2) but how do i do b.??

    i can use u'=u from part a, but im sure if this is what i have to do
  5. May 21, 2009 #4
    I think you are making it harder for yourself than it actually is.

    Just use simple velocity addition.
  6. May 21, 2009 #5


    User Avatar
    Science Advisor

    And what do YOU mean by "simple velocity addition"? It looks to me like that is what he is trying to do!

    Fredrick08, yes, you use the same formula again, this time with one of the velocities given by 2v/(1+v^2/c^2) and the other by v.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook